Fastest way of data processing is SP or Pentaho DI tools?

I am working on a BI project using MySQL for data warehousing. we are using pentaho DI tool for ETL. I wanted to process huge records My boss said me instead of using GROUP BY clause use ETL tool. Which will works fast? whether by Stored Procedure or by Pentaho tools?

ETL tools ultimately generate SQL or call SQL APIs to do the job. But, they do in optimized manner. They also let you manage data extraction with graphical aid. It is your choice- SP or tool- depending on what your need is.

Hi Abhay,
I think it would be wise to perform the ETL step wise, by limiting the size
to 5GB per ETL Transaction 15 times = 150 GB.
Also make sure that Numeric oriented columns are always processed first to
help speed up the process.
Good Luck :)
Cheers!
Anil Mahadev